Click "Customize-Customize Ceiling" and select the room to enter the ceiling customization interface. Use the drawing tool above to draw a shape on the ceiling. Then you could type in the value in the Extrusion input box to form the thickness. After that, left-click to select the shape and click "Duplicate" to duplicate it. To create an array, select the shape and click on "Array", then enter the value for distance and array number - in this way an array of shapes will be formed.